Why be diurnal? Shifts in activity time enable young cane toads to evade cannibalistic conspecifics

Pizzatto, Lígia; Child, Travis; Shine, Richard

doi:10.1093/beheco/arn060

Cited by 58 publications

(52 citation statements)

References 51 publications

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“…Cane toads breed in temporary and permanent ponds across this area, spawning most frequently at the end of the wet-season, as pond levels begin to fall; but they also can breed during the dry season [42], (M. R. Crossland and E. Cabrera-Guzmán unpublished data). Toad metamorphs (the first terrestrial phase, immediately after transformation from the tadpole) are mainly diurnal [62] and remain near the edge of natal ponds during the dry season [63]. They disperse through the wider landscape during the wet season [51], [63], [64] but often remain close to the pond from which they emerged [52].…”

Section: Methodsmentioning

confidence: 99%

Larger Body Size at Metamorphosis Enhances Survival, Growth and Performance of Young Cane Toads (Rhinella marina)

et al. 2013

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Body size at metamorphosis is a key trait in species (such as many anurans) with biphasic life-histories. Experimental studies have shown that metamorph size is highly plastic, depending upon larval density and environmental conditions (e.g. temperature, food supply, water quality, chemical cues from conspecifics, predators and competitors). To test the hypothesis that this developmental plasticity is adaptive, or to determine if inducing plasticity can be used to control an invasive species, we need to know whether or not a metamorphosing anuran’s body size influences its subsequent viability. For logistical reasons, there are few data on this topic under field conditions. We studied cane toads (Rhinella marina) within their invasive Australian range. Metamorph body size is highly plastic in this species, and our laboratory studies showed that larger metamorphs had better locomotor performance (both on land and in the water), and were more adept at catching and consuming prey. In mark-recapture trials in outdoor enclosures, larger body size enhanced metamorph survival and growth rate under some seasonal conditions. Larger metamorphs maintained their size advantage over smaller siblings for at least a month. Our data support the critical but rarely-tested assumption that all else being equal, larger body size at metamorphosis is likely to enhance an individual’s long term viability. Thus, manipulations to reduce body size at metamorphosis in cane toads may help to reduce the ecological impact of this invasive species.

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Section: Methodsmentioning

confidence: 99%

Larger Body Size at Metamorphosis Enhances Survival, Growth and Performance of Young Cane Toads (Rhinella marina)

et al. 2013

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“…Juveniles of another invasive anuran, Rhinella marina, are also known to avoid cannibalistic adults. In this case, juveniles try to segregate from adults by changing temporal activity: their activity is diurnal while adults are nocturnal (Pizzatto et al 2008). Nonetheless, the difference in microhabitat use between adults and juveniles may be related to thermoregulation, which can be achieved by changes in body posture to use warmer pond water as a heat source (Lillywhite 1970).…”

Section: Discussionmentioning

confidence: 99%

Reproductive phenology of the American Bullfrog in subtropical Brazil: photoperiod as a main determinant of seasonal activity

Medeiros

Both

Kaefer

et al. 2016

An. Acad. Bras. Ciênc.

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The North American bullfrog Lithobates catesbeianus continues to invade ecosystems worldwide, potentially causing population declines and even extinctions. Within its native distribution, bullfrogs show prolonged reproductive seasons and high fertility. However, data on breeding biology of bullfrogs ex-situ in invaded localities mainly comes from anecdotal reports. Understanding how invasive species are adjusting their life histories to new colonized environments is important for conservation purposes. Here we describe temporal and spatial abundance, calling activity, spawning and tadpole distribution of bullfrogs in southern Brazil. Eighteen samplings occurred during one year. The abundance of individuals was positively related to longer photoperiods and higher temperatures. Reproductive activity was also positively associated with longer photoperiods. Calling sites, spawning and tadpoles were associated with microhabitats presenting hydrophytes, which may provide shelter and thermal stability to bullfrogs. The reproductive seasonal activity of bullfrogs can be highly variable across its growing geographical range, but in subtropical Brazil it is associated with photoperiod, a highly predictable abiotic determinant. In our study area, bullfrogs presented a breeding season twice as long as that observed in some native localities. We suggest that management strategies directed to bullfrog populations must consider the habitat structures and seasonal regimes determined by each invaded environment.

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“…During the day the small toads can make use of their adaptive coloring to advertise toxicity and discourage predators ( Bufo bufo: [57]). Diurnal behavior can also allow young toads to avoid cannibalistic older toads ( Bufo marinus: [152]).…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, there is growing evidence that within-species competition can influence the timing of an individual’s activity within the species’ normal active period (called “Temporal Partitioning”; [98]). This temporal partitioning regularly results in the dominant individual gaining primary access to the early part of the active period, whereas lower-ranking individuals are shunted to either a more unconsolidated or delayed activity pattern ( bellbirds : [42], trout: [6], rats: [25]), in a manner that also resembles the division of time between younger and older individuals in the examples presented above ( toads: [57, 152]). As a result, this temporal partitioning allows dominant individuals to forage during times when there are higher rewards ( bellbirds: [42], trout: [6]), whereas lower-ranking individuals can gain access to resources during a time when there is less personal risk of intimidation and attack (bellbirds: [42]).…”

Section: Discussionmentioning

confidence: 99%

The neuroendocrine control of the circadian system: Adolescent chronotype

Hagenauer¹,

Lee²

2012

Frontiers in Neuroendocrinology

105

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Scientists, public health and school officials are paying growing attention to the mechanism underlying the delayed sleep patterns common in human adolescents. Data suggest that a propensity towards evening chronotype develops during puberty, and may be caused by developmental alterations in internal daily timekeeping. New support for this theory has emerged from recent studies which show that pubertal changes in chronotype occur in many laboratory species similar to human adolescents. Using these species as models, we find that pubertal changes in chronotype differ by sex, are internally generated, and driven by reproductive hormones. These chronotype changes are accompanied by alterations in the fundamental properties of the circadian timekeeping system, including endogenous rhythm period and sensitivity to environmental time cues. After comparing the developmental progression of chronotype in different species, we propose a theory regarding the ecological relevance of adolescent chronotype, and provide suggestions for improving the sleep of human adolescents.

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Why be diurnal? Shifts in activity time enable young cane toads to evade cannibalistic conspecifics

Cited by 58 publications

References 51 publications

Larger Body Size at Metamorphosis Enhances Survival, Growth and Performance of Young Cane Toads (Rhinella marina)

Larger Body Size at Metamorphosis Enhances Survival, Growth and Performance of Young Cane Toads (Rhinella marina)

Reproductive phenology of the American Bullfrog in subtropical Brazil: photoperiod as a main determinant of seasonal activity

The neuroendocrine control of the circadian system: Adolescent chronotype

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